This invention relates generally to automotive safety restraint assemblies and more particularly, to an improved inflatable knee bolster module assembly such as may be useful in automotive safety restraint systems.
It is well known to protect a vehicle occupant using inflatable restraint systems which incorporate a cushion or bag, e.g., an "airbag cushion," that is inflated or expanded with gas such as when the vehicle encounters a sudden deceleration, such as in the event of a collision. Such systems commonly comprise an inflatable airbag module stored behind the instrument panel of the vehicle. In such modules, the associated airbag cushion is normally housed in an uninflated and folded condition to minimize space requirements. Upon actuation of the system, such as in the event of a collision by the vehicle, the cushion begins to be inflated in a matter of no more than a few milliseconds with gas produced or supplied by a device commonly referred to as an "inflator." This causes the airbag cushion to be deployed as a protective cushion for occupants within the vehicle passenger compartment.
As installed behind the vehicle instrument panel, a folded airbag cushion and an associated inflator device are typically contained within a module assembly reaction canister, which canister is commonly provided with a generally rectangular cover. The cover also comprises the cover or door for an airbag deployment opening that is formed in a portion of the instrument panel.
Automotive vehicles provided with inflatable airbag cushion safety restraint devices have commonly been designed with a stationary panel, located on a downward and forwardly inclined portion of the instrument panel, which panel acts as a knee crush zone. The portion of the instrument panel enclosed in the knee crush zone is oftentimes classified or referred to as a "knee bolster." During a crash, momentum may cause an occupant to move forward such that the legs of the occupant contact the knee bolster. As a result, such knee bolsters can desirably prevent the occupant from submarining beneath the inflated airbag. With such contact, the knee bolster may desirably deform under the load such as to absorb energy and minimize the forces acting on the legs of the occupant.
The use of a crushable stationary panel on the instrument panel of an automotive vehicle to provide a knee crush zone or bolster can be disadvantageous in a number of respects. For example, such a construction can serve to reduce the distance between the knees of an occupant and the instrument panel. Such a reduction may detract from and diminish the amount of leg room and the feeling of roominess the occupant would prefer to retain.
As a result, there has been a need and a demand for improved knee bolster assemblies.
At least partially in response to such need. Airbag activated knee bolsters such as disclosed in commonly assigned Lang et al., U.S. Pat. No. 5,536,043, issued Jul. 16, 1996, and which patent disclosure is fully incorporated herein by reference, have been developed.
At least certain prior art inflatable knee bolster assemblies utilize retainer rings and a plurality of fasteners such as in the form of nuts, bolts or the like to attach the inflatable knee bolster cushion to either or both the associated knee bolster assembly module housing and the associated knee bolster panel or associated load distributor panel.
FIG. 1 illustrates a prior art knee bolster assembly, generally designated by the reference numeral 10 involving the attachment of a knee bag cushion 12 with an associated bolster panel 14 and an associated inflator 16, respectively.
With respect to the attachment of the knee bag cushion 12 with the bolster panel 14, the cushion 12 is secured between the bolster panel 14 and an associated bolster-side retainer plate or ring 20. In particular, the bolster panel 14 is provided with studs 22 which extend through the cushion 12 and through clearance holes 24 provided in the bolster-side retainer plate 20. Attachment nuts 26 are applied to the bolster panel studs 2, thereby clamping the cushion 12 between the bolster panel 14 and the bolster-side retainer ring 20.
With respect to the attachment of the knee bag cushion 12 with the inflator 16, the inflator 16 includes a circumferential attachment flange 30 to which is applied an annular reaction housing 32, also sometimes referred to as a "reaction plate." The cushion 12 is secured between the reaction plate 32 and an associated inflator-side retainer plate or ring 34 by means of rivets 36 or the like, such as is known in the art and such as may extend from the retainer ring 34. For examples the rivets 36 can be sequentially passed through the cushion 12, the reaction plate 32 and the inflator attachment flange 30 and then secured with associated attachment nuts 40.
As will be. appreciated, such attachment operations may be more difficult than desired as, for example, the bolster panel retainer plate 20 and the associated attachment nuts 26 are inside the cushion 12 and access to this interior region is through the relatively small inflator opening to the cushion. Further, the use of such multiple part fastening systems can be more complicated and costly than desired for efficient mass production.
FIG. 2 illustrates the assembly 10 of FIG. 1 after inflation of the cushion 12. As shown in FIG. 2, upon inflation of the cushion 12, large, generally triangular shaped voids 44 can occur or be formed between the cushion 12 and the bolster panel 14. As observed in previous tests, such an assembly can cause or result in undesired rotation of the bolster panel 14 relative to the retainer 20, for example, as signified by the arrows 46. As a result, the assembly 10 may experience or exhibit greater than desired instability.
Commonly assigned Schneider, U.S. Pat. No. 5,630,621, the disclosure of which is fully incorporated herein by reference, discloses a knee bolster assembly which advantageously overcomes at least some of the shortcomings or limitations of such earlier knee bolster assembly designs. In particular, this patent discloses a knee bolster assembly which advantageously eliminates the need for a bolster-side retainer and associated fasteners for attaching a bolster cushion to an associated bolster panel. In particular, it discloses attaching a bolster cushion to an associated bolster panel via the use of a rod and channel design. Further, as disclosed, such a knee bolster assembly can advantageously prevent the creation of undesirable voids which reduce assembly stability.
There is, however, a continuing need and demand for further improved inflatable knee bolster module assemblies. In particular, there is a need and a demand for improved inflatable knee bolster module assemblies such as may desirably accomplish or achieve one or more of the following objectives: simplify assembly and construction. reduce or minimize the costs associated therewith and increase assembly performance.